A scanner is an image input equipment that optically scans storage media, such as documents, drawings, photos, films and the like, and converts analog signals indicative of the intensity of a light reflected or transmitted to digital signals to thereby input digitized images. When in use, the image scanner is interfaced with a computer.
Conventional image scanners are adapted to scan one surface of a medium by keeping the medium immovable and displacing an image sensor, e.g., a charged coupled device (CCD) or an amorphous semiconductor, with respect to the medium. In case of a medium having a size similar to that of a credit card, for example, an identification card or a name card, the image scanners act to scan one surface of the medium while loading the medium to the image sensor through the actuation of a roll feed.
There have been usually employed card reader writers, examples of which include an automated teller machine, a card telephone and a ticketing machine each adapted for reading and writing data from and on a magnetic card as an example of the media. The magnetic card is comprised of a plastic card and a magnetic stripe attached to the plastic card for storage of data in a readable and writable manner. Under Article 7811 of the regulations prescribed by the International Standardization Organization, the magnetic stripe is attached along one lateral side of the plastic card. The data stored in the magnetic stripe are read by a magnetic stripe reader (MSR) of a card reader writer.
Such a magnetic card is provided with varying kinds of forgery-proof elements, e.g., a barcode, a hologram and so forth, cryptographically marked on one surface thereof for forgery prevention purpose. Images of the forgery-proof elements are scanned and converted to image data by means of an image sensor, which image data are then deciphered by a computer program and compared with character information of the magnetic card to verify the authenticity the magnetic card.
However, the conventional image scanners are designed to sequentially scan one and the other surfaces of a medium one by one, which is highly time-consuming and cumbersome-to-use. In particular, the speed at which an image sensor or a medium is loaded imposes a significant restriction on the responsiveness of the image sensor. In other words, it is very difficult to shorten the scanning time due to the design constraint that the loading speed should be inversely proportional to the resolution of the image sensor in order to obtain image data of increased accuracy.
In the meantime, at the time of loading deformed magnetic cards, for example, bent or crushed magnetic cards, a feed roller and an idle roller of a roll feed are spaced apart from each other to accommodate the deformation of the magnetic card. This leads to unrestrained movement and reduced friction, namely, slipping, of the magnetic cards, which may cause a problem of jitter. Moreover, what is called a spacing loss is created between the magnetic cards and the magnetic stripe reader, which may give rise to an error in reading out the data stored in the magnetic cards.
Furthermore, the magnetic cards exhibit deviation in size from manufacturer to manufacturer. The size deviation poses a problem in that the magnetic stripe reader may suffer from a tracking error when tracking the magnetic stripe. The conventional image scanners are not provided with any mechanism that can load the magnetic cards along a reference loading line of a track to assure accurate tracking of the magnetic stripe reader relative to the magnetic stripe. Thus, the image scanners have no ability to control the unrestrained movement of the magnetic cards and to compensate the size deviation of the magnetic cards. As a result, a loading error may be incurred that the magnetic cards are not loaded rectilinearly but turned in a loading process. In addition, severe distortion appears in the image acquired and the magnetic cards are often jammed when loaded.